I bought a second-hand DB4 a few days ago, and had the same problems on Ryzen machine. I opened a ticket with A&H support, and they provided me with older audio firmware 1.3.9, saying it might work. As soon as I installed it, all the problems on Ryzen Win10 machine were gone, and now everything works smoothly!
So if you (or anyone else), still have a problem, I suggest writing to them and they will send you the firmware.
